1. Technical Field
The present invention relates to an aqueous ink for inkjet used in inkjet recording methods, and an inkjet recorder and an inkjet recoding method using the ink.
2. Description of the Related Art
Inkjet printers have been widely used as digital signal output equipment in general homes because of having advantages such as low noise, low running cost, and easiness of color printing. In recent years, inkjet techniques have been increasingly utilized not only in such homes but also for industrial applications such as a display, a poster, and a bulletin board.
As such inks, for example, solvent-based inkjet inks using an organic solvent as a vehicle, and ultraviolet curable inkjet inks including a polymerizable monomer as a main component have been ever used widely.
However, the solvent-based inkjet inks are not preferable in terms of environmental load because the solvent is evaporated in the atmosphere, and the ultraviolet curable inkjet inks have limited application fields because they may have skin sensitizing properties depending on the monomer to be used and an expensive ultraviolet irradiation apparatus is required to be incorporated to the main body of a printer.
In view of such background, there have been recently developed inkjet inks capable of being used in the industrial applications, which are aqueous inks for inkjet recording which give less environmental load and which have been widely used as inkjet inks for household use.
Examples of such known arts are disclosed in Japanese published unexamined applications Nos. JP-2005-220352-A and JP-2001-094082-A.
However, such aqueous inks generally have several drawbacks pointed out in terms of reliability, as compared with the solvent-based inkjet inks. Namely, when the ink dries at a nozzle surface, resin particles in the ink begins to melt and the ink increases in viscosity at the surface, resulting in difficulty of ink discharge.
In order to solve this problem, a solvent having high moisture retainability such as glycerin is thought to be added. However, nonpermeable substrates an ink does not substantially permeate are used in many cases in the industrial applications. Such a solvent having high boiling point causes the resultant ink to poorly dry, and it is easily conceivable blocking occurs, i.e., the ink transfers to the back of prints when overlapped or rolled.
Further, the ink has a problem not only before discharged but also after discharged. Namely, the ink on the nonpermeable substrates needs to have high toughness because of being supposed to be exposed outdoors.